This, I believe, is what they call a no-brainer. Pirates? Metal? Pirates playing metal? What's not to like?

The answer, if you have a sense of humour and want more from life than Fleet Foxes can offer, is: nothing. Where other genres come and go, heavy metal survives by throwing up variations on a relatively tried and tested formula. The latest is pirate metal, which adheres to the rules of big riffs, big hair and devotion to volume but with an added style and subject matter entirely influenced by the swashbuckling buccaneers of yore. Think Captain Hook, Blackbeard and Long John Silver. Maybe even Johnny Depp impersonating Kirk Hammett instead of Keith Richards.

That's because pirate metal cares little about historical accuracy and instead takes its cue from fantasy portraits of pirates in literature, film and folklore. Current exponents include Swashbuckle whose album Back to the Noose (sample song titles: Peg-Leg Stomp, It Came from the Deep) is out this month. It walks the plank on just the right side of ridiculous and is available for free online. Which isn't particularly piratical.

Similarly Scotland's Alestorm rock the shanty-folk-metal crossover hard on new album Black Sails at Midnight (sample song titles: Captain Morgan's Revenge, Wenches and Mead) despite the appearance of that most non-threatening of instruments, the keytar. The end result is a bit like a rum-soaked Gogol Bordello covering Celtic Frost: frantic, fierce and fun.

Pirate metal is not new, however. It stretches back more than 20 years to when German power-metal band, Running Wild, released their Under Jolly Roger album in 1987 and made the link between metal and seafaring ne'er-do-wells. They did this through the use of pirate jargon, an interest that grew, according to their Wikipedia entry, out of "mainman Rolf Kasparek's commitment to ideals of anarchism and libertarian socialism".

It all sort of makes sense when you consider the similarities between good ole metal and bad ole raping, pillaging and marauding: a casual approach to sartorial matters, a fondness for getting sweaty and primal alongside other men, the freedom of the high seas/road, and a relaxed attitude towards diction. Barrels of booze. Comely wenches. STDs.

Maybe it's just the freewheeling outlaw nature of a semi-fantasy world that makes it so appealing to new bands, like Canada's Verbal Deception (sample songs: Pirate Attack, High Seas, Under the Black Flag), who don't actually want to be pirates but instead draw inspiration from the mythology, much like current metal torchbearers Mastodon are inspired by the whaling world of Melville's Moby Dick.

Piracy has infiltrated other genres too. The late and rather great Liverpool hardcore band Walk the Plank mixed pirate imagery into their old-school brutality. Fittingly, they played their last ever show on a ship in the Albert Dock. Then there are perennial punks Goldblade, whose last album was entitled Mutiny and featured a sea shanty version of the album's title track, built on lyrics like "Avast ye swabs and clean the decks …" And let's not forget the Sex Pistols' Friggin' in the Riggin'. Not their finest moment, admittedly.

Of course, any self-respecting progressive pirate metaller today should really be dressing up in the everyday clothes of a broke Somalian and waving an AK47 about while singing songs about the injustices of the World Bank, trade embargos and $3m dollar ransoms. But, you know, where's the glamour in that?